1. Field of the Invention
The present invention relates to an engine unit for outputting drive force in a straddle-type vehicle.
2. Description of Related Art
The engine unit of a straddle-type vehicle (for example, a motorcycle) may include a belt-type continuously variable transmission. A belt-type continuously variable transmission is generally provided with a driving side pulley mounted on a drive shaft, a driven side pulley mounted on a driven shaft and a belt that is looped around the driving and driven side pulleys and that transmits drive force to the driven side pulley from the driving side pulley.
In an engine unit provided with a belt-type continuously variable transmission, Japanese Unexamined Patent Publication No. 2002-19669 proposes supporting the end portion of the drive shaft and the end portion of the driven shaft with a case for housing the continuously variable transmission.
However, when the belt is tightly looped so as not to cause a transmission loss of drive force between the driving and driven side pulleys, force in a direction to bring the drive shaft close to the driven shaft is applied to the drive and driven shafts by the belt, which raises the possibility that the drive and driven shafts will be slightly deflected. To prevent such deflection, the rigidity of the whole of the case for supporting these shafts is increased, which raises the possibility that the productivity of the engine unit will be decreased.